The present invention relates to a self-supporting trailer for connection to a towing vehicle and particularly relates to a self-supporting steerable trailer system wherein transmission of vertical and lateral loadings from the trailer to the towing vehicle are substantially minimized or eliminated.
With the advent of lighter weight towing vehicles for transporting campers and recreational vehicles of all varieties, as well as commercial and industrial trailers, it has become necessary to consider reducing the forces, both lateral and vertical, on the towing vehicle at its hitch point, as well as the drawbar forces generated by towing the trailer, in the design of any new trailer system. For example, the transmission of varying vertical loadings from the trailer through the drawbar and trailer hitch to the towing vehicle may subject the towing vehicle to dangerous rocking or vertical motion sufficient to impair or prevent control of the towing vehicle and its towed trailer. This variable vertical hitch weight is particularly critical in the case of trailers or campers supported solely by wheels located substantially medially of their lengths. The hitch of this type of trailer or camper subjects the towing vehicle to substantial and variable vertical loadings caused essentially by a rocking motion about the trailer wheel supports. This potentially dangerous condition is exacerbated when such trailer is coupled to a lightweight towing vehicle. Also, lateral loads induced by centrifugal force under turn conditions, cross and quartering winds, and other forces tend to displace the trailer and the towing vehicle laterally and these pose control and consequent safety problems for the operator of the light weight towing vehicle.
Prior trailer systems have simply not addressed themselves to the problems inherent in utilizing lightweight towing vehicles and are therefore not particularly adaptable for use with the newer lightweight towing vehicles. For example, U.S. Pat. No. 2,561,644 issued July 24, 1951, discloses a dolly for supporting the forward end of a trailer in a manner which relieves the towing vehicle of the weight of the forward end of the trailer. Yet the structure disclosed in that patent transmits a vertical downward load of predetermined magnitude on the hitch of the towing vehicle. Consequently, vertical hitch loadings of varying magnitudes obtain and, as noted previously, have deleterious effects on the control and safety of the towing vehicle, particularly a lightweight towing vehicle. Further, this U.S. patent provides a steering arm connecting between the towing vehicle and the steerable dolly at the forward end of the trailer. However, variations in the hitch angle in this construction would apparently cause a change in steering direction of the dolly which would not be in accordance with the turning movement of the towing vehicle. The foregoing described and other prior trailering systems thus do not appear to be particularly useful in the design of a trailer system for use with lightweight towing vehicles where the reduction or elimination of the vertical and lateral forces acting on the hitch of the towing vehicle is advantageous and necessary.